Methods and apparatus for polishing a notch of a substrate

ABSTRACT

Apparatus and methods are provided to polish a notch of a substrate. The invention includes a polishing head adapted to apply a polishing tape against the notch of the substrate, including: a plunger; and an actuator, wherein the actuator is adapted to move the plunger with respect to the polishing tape. Numerous other aspects are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to the following commonly-assigned,co-pending U.S. Patent Applications, each of which is herebyincorporated herein by reference in its entirety for all purposes:

U.S. patent application Ser. No. 12/124,137, filed May 20, 2008,entitled “METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATEUSING A POLISHING PAD” (Attorney Docket No. 10674);

U.S. patent application Ser. No. ______, filed Oct. 24, 2008, entitled“METHODS AND APPARATUS FOR POLISHING AN EDGE AND/OR NOTCH OF ASUBSTRATE” (Attorney Docket No. 10671/L);

U.S. patent application Ser. No. ______, filed Oct. 24, 2008, entitled“METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATE WITH AMANDREL” (Attorney Docket No. 10672/L); and

U.S. patent application Ser. No. ______, filed Oct. 24, 2008, entitled“METHODS AND APPARATUS FOR POLISHING A NOTCH OF A SUBSTRATE WITH ANABRASIVE CORD” (Attorney Docket No. 10673/L).

FIELD OF THE INVENTION

The present invention relates generally to substrate processing, andmore particularly to methods and apparatus for cleaning a notch in anedge of a substrate.

BACKGROUND OF THE INVENTION

Conventional systems, which contact a notch in the edge of a substratewith an abrasive tape to clean the notch, may not be able to contact allparts of the notch with the abrasive tape. As a result, theseconventional systems may not be able to clean or polish all parts of thenotch. Accordingly, effective methods and apparatus for cleaning orpolishing all parts of notches in the edges of substrates are desired.

SUMMARY OF THE INVENTION

In some aspects of the invention an apparatus is provided for polishinga notch of a substrate. The apparatus includes a polishing head adaptedto apply a polishing tape against the notch of the substrate. Thepolishing head includes a plunger; and an actuator, wherein the actuatoris adapted to move the plunger with respect to the polishing tape.

In other aspects of the invention, a system is provided for polishing anotch of a substrate. The system includes a substrate support adapted torotate a substrate; and a polishing head adapted to apply a polishingtape against the notch of the substrate. The polishing head includes aplunger; and an actuator, wherein the actuator is adapted to press theplunger into the polishing tape and thereby press the polishing tapeagainst the notch. The system also includes a controller adapted tooperate the rotation of the substrate and the actuator.

In yet other aspects of the invention, a method is provided forpolishing a notch of a substrate. The method includes (1) securing asubstrate on a support; (2) aligning a substrate notch with a polishinghead including a plunger; (3) pressing a polishing tape against a notchwith the plunger; and (4) advancing the polishing tape as the polishingtape is pressed against the notch.

Other features and aspects of the present invention will become morefully apparent from the following detailed description, the appendedclaim and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a cross-section of a portion of asubstrate.

FIG. 2 is a schematic plan view of an embodiment of a system forpolishing parts of a substrate, including major surfaces, edge, bevel,and notch.

FIG. 3 is a schematic perspective view of an embodiment of a polishingapparatus for polishing a substrate notch.

FIG. 4 is a schematic illustration of part of a substrate, including asubstrate notch.

FIG. 5 is a schematic perspective view of a portion of an embodiment ofthe notch polishing apparatus of FIG. 3.

FIG. 6 is a plan view of an example of polishing tape being pressed intoa substrate notch by a plunger in accordance with some embodiments ofthe present invention.

FIG. 7 is a plan view of an example of polishing tape being pressed intoa substrate notch by an angled plunger in accordance with someembodiments of the present invention.

FIG. 8 is a schematic perspective view of another embodiment of apolishing apparatus for polishing a substrate notch.

FIG. 9 is a flow chart of a method for polishing a substrate notch inaccordance with the present invention.

DETAILED DESCRIPTION

Substrates used in semiconductor processing often have films and/orsurface defects which it is helpful to remove prior to subsequentprocessing steps. These films and defects may occur on the edge of asubstrate, including notches formed thereon.

In some embodiments, the present invention provides apparatus andmethods that effectively adapt to various shapes of notches found indifferent substrates, ensure good contact of a polishing or abrasivefilm or tape with all sections of a substrate notch region, and removethin films and surface defects at a substrate notch. In one or moreembodiments, a polishing plunger may be provided. The polishing plungermay be adapted to press a moving polishing tape against the substratenotch. The polishing plunger may substantially conform to the shape ofthe substrate notch, such that the polishing tape contacts all portionsof the notch.

Turning to FIG. 1, a substrate 100 may include two major surfaces 102,102′ and an edge 104. Each major surface 102, 102′ of the substrate 100may include a device region 106, 106′ and an exclusion region 108, 108′.(Typically however, only one of the two major surfaces 102, 102′ willinclude a device region and an exclusion region.) The exclusion regions108, 108′ may serve as buffers between the device regions 106, 106′ andthe edge 104. The edge 104 of the substrate 100 may include an outeredge 110 and bevels 112, 114. The bevels 112, 114 may be located betweenthe outer edge 110 and the exclusion regions 108, 108′ of the two majorsurfaces 102, 102′. A notch 116 may be located in the outer edge 110 ofthe substrate 100. In some embodiments, the present invention may beadapted for use with a system adapted to clean and/or polish the outeredge 110 and at least one bevel 112, 114 of the substrate 100 withoutaffecting the device regions 106, 106′. In some embodiments, all or partof the exclusion regions 108, 108′ may be cleaned or polished as well.

FIG. 2 is a schematic plan view of an embodiment of a system 200 forpolishing parts of the substrate 100, including the major surfaces 102,102′, the edge 104, and the notch 116. The system 200 includes threepolishing apparatuses 202, each including a polishing head 204. However,any number and type of apparatus 202/heads 204 may be used in anypracticable combination. In addition, in such multi-head embodiments,each head 204 may use a differently configured or type of a polishingtape (e.g., different grits, materials, tensions, pressures, etc.) tocontact and polish the substrate edge 104 and/or notch 116. Any numberof heads 204 may be used concurrently, individually, and/or in anysequence. The heads 204 may be disposed in different positions and/or indifferent orientations (e.g., aligned with the substrate edge 104 and/ornotch 116, normal to the substrate edge 104 and/or notch 116, angledrelative to the substrate edge 104 and/or notch 116, etc.) to allowpolishing tape, pushed by a plunger in some embodiments (FIG. 3), topolish different portions of the substrate edge 104 and/or notch 116.

In some embodiments, one or more of the heads 204 may be adapted to beoscillated or moved (e.g., pivoted or angularly translated about atangential axis of the substrate 102 and/or circumferentially relativeto the substrate 102) around or along the substrate edge 104 and/ornotch 116 so as to polish different portions of the substrate edge 104and/or notch 116. In some embodiments, one or more of the heads 204 maybe adapted to continuously or intermittently oscillate between thevarious positions. Alternatively, one or more of the heads 204 may befixed and/or only adjusted while the substrate 102 is not being rotated.In yet other embodiments, the substrate 102 may be held fixed while oneor more of the heads 204 oscillate (as described above) as well asrotate circumferentially around the substrate 102. This movement may beunder the direction of a programmed or user operated controller 206,described below. Different heads 204 may be used for differentsubstrates 100 or different types of substrates 100.

As described above, the system 200 may further include the controller206, (e.g., a programmed computer, a programmed processor, amicrocontroller, a gate array, a logic circuit, an embedded real timeprocessor, etc.), which may control the driver(s) used to rotate thesubstrate 100 and/or the actuator(s) used to push a polishing plunger(s)(FIG. 3) against the substrate edge 104 and/or notch 116. Note that thecontroller 206 may be coupled (e.g., electrically, mechanically,pneumatically, hydraulically, etc.) to each of a plurality of actuators.Likewise, the controller 206 may be adapted to receive feedback signalsfrom one or more drivers and/or actuators, that indicate the amount ofenergy being exerted to rotate the substrate 100 (e.g., rotate a vacuumchuck holding the substrate 100) and/or actuate the actuator(s) to pushthe polishing plunger (FIG. 3) against the substrate notch 116. Asdescribed further below, these feedback signals may be employed todetermine when a particular layer of film has been removed from the edge104 and/or notch 116 of the substrate 100 and/or whether a sufficientamount of substrate polishing has occurred.

As mentioned above, substrate polishing may be performed using one ormore polishing apparatuses 202. In one or more embodiments, a pluralityof polishing apparatuses 202 may be employed, in which each polishingapparatus 202 may have similar or different characteristics and/ormechanisms. In the latter case, particular polishing apparatuses 202 maybe employed for specific operations. For example, one or more polishingapparatuses 202 may be adapted to perform relatively rough polishingand/or adjustments while another one or more polishing apparatus 202 maybe adapted to perform relatively fine polishing and/or adjustments.Polishing apparatuses 202 may be used in sequence so that, for example,a rough polishing procedure may be performed initially and a finepolishing procedure may be employed subsequently as needed or accordingto a polishing recipe. The plurality of polishing apparatuses 202 may belocated in a single chamber or module, as shown herein, oralternatively, one or more polishing apparatuses 202 may be located inseparate chambers or modules. Where multiple chambers are employed, arobot or another type of transfer mechanism may be employed to movesubstrates 100 between the chambers so that polishing apparatuses 202 inthe separate chambers may be used in series or otherwise.

Substrate [edge/notch] polishing may be performed using one or morepolishing apparatuses 202. In one or more embodiments, a plurality ofpolishing apparatuses 202 may be employed, in which each polishingapparatus 202 may have similar or different characteristics and/ormechanisms. In the latter case, particular polishing apparatuses 202 maybe employed for specific operations. For example, one or more of aplurality of polishing apparatuses 202 may be adapted to performrelatively rough polishing and/or adjustments while another one or moreof the plurality of polishing apparatus 202 may be adapted to performrelatively fine polishing and/or adjustments. Polishing apparatuses 202may be used in sequence so that, for example, a rough polishingprocedure may be performed initially and a fine polishing procedure maybe employed subsequently to make adjustments to a relatively roughpolish as needed or according to a polishing recipe. The plurality ofpolishing apparatuses 202 may be located in a single chamber or module,as shown herein, or alternatively, one or more polishing apparatuses 202may be located in separate chambers or modules. Where multiple chambersare employed, a robot or another type of transfer mechanism may beemployed to move substrates 100 between the chambers so that polishingapparatuses 202 in the separate chambers may be used in series orotherwise.

FIG. 3 is a schematic perspective view of an embodiment of a polishingapparatus 300 for polishing a substrate edge 104 and/or notch 116. Thepolishing apparatus 300 may include a substrate driver 302 (e.g., aservomotor, gear, belt, chain, etc.), which may be mounted on a pedestal304. A support 306 (e.g., a vacuum chuck) may be coupled (e.g., rigidly)to a shaft (not shown) of the substrate driver 302. The support 306 maysupport the substrate 100, for example. The substrate driver 302 mayrotate the substrate 100, via the support 306, about a center 308 of thesubstrate 100 or another suitable axis. The substrate driver 302 may beconnected to a substrate driver control unit, such as the controller 206(FIG. 2), for example, which may control the angular displacement,angular velocity, and angular acceleration of the substrate 100. Thepolishing apparatus 300 may further include a polishing arm 310 alignedin the horizontal plane approximately tangential to the substrate edge104 and supported by a frame 312. The frame 312 may be coupled at oneend to a polishing head driver 309. In other embodiments, the polishingarm 310 may be aligned differently, for example, vertically or at anangle with respect to the horizontal plane. The polishing arm 310 mayinclude a polishing head section 314 (‘head’). The polishing head 314may include a plunger 316. The plunger 316 may be shaped to correspondto the shape of the notch 116, described further below. The plunger 316may be moved towards or away from the substrate 100 by an actuator (FIG.5) (e.g., hydraulic actuator, pneumatic actuator, servomotor, etc.).Polishing tape 318, may wrap around the polishing head 314, and guiderollers 320, 322 and over the plunger 316, and be tensioned betweensupply and take-up spools 324, 326. The supply and take-up spools 324,326 may be driven by supply and take-up spool drivers 328, 330 (e.g.,servomotors), respectively. The supply and take-up spool drivers 328,330, may be moved continuously or indexed to precisely control theamount of the polishing tape 318 that is advanced over the polishinghead 314 from, for example, the supply and take-up spools 324, 326, inorder to polish the substrate notch 116. In some embodiments, as thepolishing tape 318 advances, the polishing tape 318 may vibrate, ineither a horizontal or vertical orientation, for example. Other suitableorientations may be used.

In one or more embodiments, the polishing tape 318 may be made from manydifferent materials, such as aluminum oxide, silicon oxide, siliconcarbide, etc. Other materials may also be used. In some embodiments,abrasives used may range, for example, from about 0.1 microns up toabout 10 microns in size or, for example, 0.5 microns to 3 microns insize, although other sizes may be used. Different widths of polishingtape 318 ranging from about 0.55 inch to about 1.5 inches may be used,although other polishing tape widths may be used. In one or moreembodiments, the polishing tape 318 may be about 0.002 to about 0.02inches thick and withstand about 1 to 5 lbs. in tension. Other polishingtapes having different thicknesses and tensile strengths may be used.The supply and take-up spools 324, 326 may have a diameter ofapproximately 3 inches and be capable of holding about 30,000 inches ofpolishing tape 318, or, for example, may have a diameter ofapproximately 1 inch and be capable of holding about 500 inches ofpolishing tape 318. Other spool dimensions may be used. The supply andtake-up spools 324, 326 may be constructed from materials such as nylon,polyurethane, polyvinyl difluoride (PVDF), etc. Other materials may alsobe used.

With reference to FIG. 4, a part of the substrate 100 containing thenotch 116 is schematically illustrated, not to scale. The notch 116 mayinclude one or more notch sides 400. The notch 116 may also include afirst notch corner or node 402 and a second notch corner or node 404.Each notch corner 402, 404 may be positioned at the intersection of thenotch side 400 and the outer perimeter of the substrate 100. The notch116 may further include a notch center 406, positioned at theintersection of the one or more notch sides 400. The notch center 406may be used to align the substrate 100 during processing. As is apparentfrom the figure, the notch 116 may exhibit large changes in curvature asit is traced from the first notch corner 402 to the second notch corner404, via the notch sides 400 and notch center 406. For this reason, itis advantageous to maintain consistent contact between the polishingtape 318 and all regions of the notch 116 indicated above duringpolishing.

Turning to FIG. 5, a schematic perspective view of a portion of anembodiment of the notch polishing apparatus 300 of FIG. 3 is provided.For reasons of clarity, only the substrate 100, the plunger 316, thepolishing tape 318, and the supply and take-up spools 324, 326 areshown. In addition, it should be pointed out that the positioning of thesupply and take-up spools 324, 326 shown herein is different than in theembodiment of the notch polishing apparatus 300 shown in FIG. 3.

However, the positioning of the supply and take-up spools 324, 326 maybe arranged in different ways and may not have a large effect on thepolishing of the notch 116. The plunger 316 may be a solid piece,resilient material, or inflatable, for example. The resilient materialmay be polyurethane foam or silicone rubber, for example. Other suitablematerials may be used. The plunger 316 may be inflated with apressurizable gas (e.g., air, nitrogen, carbon dioxide, etc.) or liquid(e.g., hydraulic fluid), or other suitable fluid. The plunger 316 mayalso be soft, rigid, and/or include or develop contours to conform tothe shape of the notch 116. The radius of the plunger 316 may beselected to ensure that the polishing tape 318 is fully pushed into thenotch 116 by the plunger 316. In some embodiments, the maximum radius ofthe plunger 316 is approximately less than 0.05 inches. In otherembodiments, the maximum radius of the plunger 316 is approximately 0.03inches or less. Any other suitable radius or dimensions may be used.

As mentioned above, the plunger 316 may be coupled to an actuator 500.The actuator 500 may be a pneumatic slide, hydraulic actuator,servomotor or any other suitable actuator 500. The actuator 500 may bemounted to the polishing head 314 or the support arm 310 for example.The operation of the actuator 500 may be controlled by the controller206, for example. As described above with regard to FIG. 3, the plunger316 may be moved toward or away from the substrate 100 by the actuator500. When moved toward the substrate 100 by the actuator 500, theplunger 316 may press the polishing tape 318 into the notch 116 andcause the polishing tape 318 to conform to the shape of the notch 116and therefore contact all of the regions of the notch 116 (FIG. 4). Theactuator 500 may include an actuator force or pressure sensor 502 formeasuring a force or a pressure exerted by the actuator 500 on theplunger 316. The actuator 500 may also be coupled to an actuator controlunit, such as the controller 206, for example. The actuator control unitmay receive a signal from the actuator force or pressure sensor 502indicative of the force or pressure exerted on the plunger 316 by theactuator 500. The actuator control unit may also regulate the force orpressure exerted by the actuator 500 as a function of this signal.Depending on the amount of force applied to the plunger 316, therigidity of the plunger 316 selected, the amount of inflation of theinflatable plunger 316, and/or amount of tension on the polishing tape318, a controlled amount of pressure may be applied to polish the notch116 as the polishing head 314 is rotated about the substrate 100.

As described above, the polishing head 314 (and therefore the plunger316) may pivot about the substrate edge 104 and/or the notch 116. Insome embodiments a center of rotation 600 (FIG. 6) of the polishing head314 may be positioned about 0.5 inches from the substrate, on a planethat goes through a center of the thickness of the substrate 100 and isparallel to a tangent line to the circumference of the substrate 100.Other suitable center of rotation positions may be used. By positioningthe center of rotation 600 a distance from the tangent line the plunger316 may create a flatter or less acute tape face than if the center ofrotation 600 were not a distance from the tangent line. By positioningthe center of rotation 600 a distance from the tangent line, the notch116 may be more effectively polished as the polishing head 314 pivotsabout the notch 116. For example, in FIG. 7, the polishing head 314 haspivoted such that the polishing tape 318 is pressed into the notch 116by an angled plunger 316. Additionally, this center of rotation positionmay more efficiently and effectively use the polishing tape 318, in thata greater surface area of the polishing tape 318 may contact, andtherefore polish, the notch 116.

In some embodiments, one or more fluid channels (not shown) (e.g., aspray nozzle or bar) may be provided to deliver chemicals and/or waterto aid in the polishing/cleaning of the notch 116, lubricate thesubstrate 100, and/or to wash away removed material. The fluid channelmay be adapted to deliver fluid to the substrate 100 and/or to thepolishing tape 318. In some embodiments, the fluid may be delivereddirectly to the notch 116. For example, one or more channels may beprovided to direct chemicals or water to the notch 116 to assist in thepolishing and/or to wash away particles resulting from the polishing.The chemicals may be sprayed directly onto the substrate 100, at thesubstrate/polishing tape interface. The fluids may be sprayed fromeither or both sides of the substrate 100 and the present invention mayemploy gravity or suction to cause the runoff not to contaminate orcontact other parts of the substrate 100 or apparatus of the invention.Fluid also may be delivered through the moveable polishing tape 318 tothe notch 116. The fluids may include deionized water which may serve asa lubricant and to flush particles away. A surfactant and/or other knowncleaning chemistries may also be included. In some embodiments, sonic(e.g., megasonic) nozzles may be used to deliver sonicated fluids to thenotch 116 or substrate edge 104 to supplement the cleaning.

Turning to FIG. 8, an alternate embodiment of the apparatus 300 shown inFIG. 3 is provided. The difference between FIG. 3 and FIG. 8 is that thesupply and take-up spools 324, 326 and supply and take-up spool drivers328, 330 shown in FIG. 3 are oriented such that as the substrate 100rotates in the xy plane, the polishing tape 318 advances in alongitudinal direction in the plus or minus z-plane. In FIG. 8 thespools 324, 326 and spool drivers 328, 330 are oriented such that thepolishing tape 318 advances in a longitudinal direction in the plus orminus y-plane.

An exemplary method 900 for cleaning and polishing the substrate notch116 is provided in FIG. 9. In step S902, the substrate 100 may bepositioned and secured on the support. In step S904, the substrate 100is rotated until the notch 116 is in alignment with the polishing head314, e.g., in alignment with the plunger 316. In step S906, the plunger316 is moved in the direction of the substrate 100 by the actuator 500,until a portion of the plunger 316 is in contact with the substratenotch 116 via the polishing tape 318, and the plunger 316 presses thepolishing tape 318 against the substrate notch 116. In step S908, thepolishing tape 318 may advance via the supply and take-up spool drivers328, 330.

Further with respect to the method 900 for cleaning and polishing thesubstrate notch 116, the pressure with which the polishing tape 318 ispressed into contact with, and against, the substrate notch 116 may bedetermined by the force or pressure applied to the plunger 316 by theactuator 500, the pressure of the fluid in the plunger 316, and/or theresilience of the plunger 316 and the polishing tape 318. As thepolishing tape 318 is advanced over the substrate notch 116, films andimperfections on the substrate notch 116 may be removed and eliminatedby abrasion. The force or pressure applied by the actuator 500, and/orthe pressure of the fluid in the plunger 316, may be adjusted by anactuator control unit and a pressure control unit, respectively, asneeded. In step S910, a polishing-head driver or the controller 112 mayrotate or pivot the polishing head 314 about the substrate notch 116 ina plane approximately perpendicular to major surfaces 102, 102′ of thesubstrate 100, in order to effectively clean and polish parts of thesubstrate notch 116 adjacent to major surfaces 102, 102′ of thesubstrate 100. The speed, direction, tension, pressing force, etc. ofthe polishing tape 318 may be adjustable, as may be the rotationaldisplacement, speed, and/or acceleration of the polishing head 314 aboutthe substrate 100. For instance, the polishing tape 318 may be advancedat one speed for a certain length, and then another speed for anotherlength. In addition, the polishing tape 318 may be translated oroscillated, or both, with constant or variable tensions and pressingforces.

The foregoing description discloses only exemplary embodiments of theinvention. Modifications of the above disclosed apparatus and methodswhich fall within the scope of the invention will be readily apparent tothose of ordinary skill in the art.

Accordingly, while the present invention has been disclosed inconnection with exemplary embodiments thereof, it should be understoodthat other embodiments may fall within the spirit and scope of theinvention, as defined by the following claim.

1. An apparatus for polishing a notch of a substrate comprising: apolishing head adapted to apply a polishing tape against the notch ofthe substrate, including: a plunger; and an actuator, wherein theactuator is adapted to move the plunger with respect to the polishingtape.
 2. The apparatus of claim 1 wherein the actuator is adapted topress the plunger into polishing tape and thereby press the polishingtape against the notch.
 3. The apparatus of claim 1 wherein thepolishing head is adapted to pivot about the notch.
 4. The apparatus ofclaim 1 wherein the plunger is adapted to pivot about the notch.
 5. Theapparatus of claim 1 wherein the polishing tape is adapted to advanceover the plunger during application of the polishing tape to the notch.6. The apparatus of claim 5 wherein the polishing tape is adapted tovibrate as the polishing tape advances over the plunger.
 7. Theapparatus of claim 1 wherein the plunger is adapted to conform thepolishing tape to a shape of the notch.
 8. The apparatus of claim 7wherein the plunger has a shape that corresponds to a shape of thenotch.
 9. The apparatus of claim 1 wherein the polishing head is adaptedto continuously oscillate around the notch.
 10. The apparatus of claim 1wherein the plunger is a pneumatic plunger.
 11. A system for polishing anotch of a substrate comprising: a substrate support adapted to rotate asubstrate; a polishing head adapted to apply a polishing tape againstthe notch of the substrate, including: a plunger; and an actuator,wherein the actuator is adapted to press the plunger into polishing tapeand thereby press the polishing tape against the notch; and a controlleradapted to operate the rotation of the substrate and the actuator. 12.The system of claim 11 wherein the controller is adapted toincrementally advance the polishing tape to the polishing head.
 13. Thesystem of claim 11 wherein the actuator includes a pressure sensoradapted to sense the pressure exerted by the actuator on the plunger.14. The system of claim 13 wherein the controller is adapted to receivea signal from the pressure sensor indicative of the pressure exerted bythe actuator on the plunger.
 15. The system of claim 11 wherein thepolishing head is adapted to pivot about the notch.
 16. The apparatus ofclaim 11 wherein the plunger is adapted to pivot about the notch. 17.The apparatus of claim 11 wherein the polishing tape is adapted toadvance over the plunger during application of the polishing tape to thenotch.
 18. The apparatus of claim 11 wherein the plunger is adapted toconform the polishing tape to a shape of the notch.
 19. The apparatus ofclaim 18 wherein the plunger has a shape that corresponds to a shape ofthe notch.
 20. A method for polishing a notch of a substrate comprising:securing a substrate on a support; aligning a substrate notch with apolishing head including a plunger; pressing a polishing tape against anotch with the plunger; and advancing the polishing tape as thepolishing tape is pressed against the notch.
 21. The method of claim 20further comprising: pivoting the polishing head about the substratenotch.
 22. The method of claim 20 further comprising: receiving a signalindicative of the pressure applied to the plunger.
 23. The method ofclaim 22 further comprising: adjusting the pressure based on thereceived signal.
 24. The method of claim 20 further comprising:vibrating the polishing tape as the polishing tape advances.
 25. Themethod of claim 20 further comprising advancing the polishing tapecontinuously.